Temporal variation of hydroxyl radical generation and 8-hydroxy-2′-deoxyguanosine formation by coarse and fine particulate matter

Abstract

Aims: To determine the induction of 8-hydroxy-2′-deoxyguanosine (8-OHdG) by fine (<2.5 µm) and coarse (10-2.5 µm) particulate matter (PM) sampled over time at one sampling location, and to relate the observed effects to the hydroxyl radical (⋅OH) generating activities and transition metal content of these samples, and to meteorological parameters. Methods: Weekly samples of coarse and fine PM were analysed for H 2 O 2 dependent ⋅OH formation using electron spin resonance (ESR) and formation of 8-OHdG in calf thymus DNA using an immunodotblot assay. Immunocytochemistry was used to determine 8-OHdG formation in A549 human epithelial lung cells. To determine temporal effects, samples from six weeks in summer and six weeks in autumn/winter were compared using ESR and the dotblot assay. Concentrations of leachable V, Cr, Fe, Ni, and Cu were determined by inductively coupled plasma mass spectrometry. Results: Both PM fractions elicited ⋅OH generation as well as 8-OHdG formation in calf thymus DNA and in A549 cells. 8-OHdG formation in the naked DNA was significantly related to ⋅OH generation, but not to metal concentrations except for copper. A significantly higher ⋅OH generation was observed for coarse PM, but not fine PM collected during the autumn/winter season; this was not due to differences in sampled mass or metal content. Specific weather conditions under which increased ⋅OH formation in the coarse mode was observed suggest that other, as yet unknown, anthropogenic components might affect the radical generating capacity of PM. Conclusions: Both coarse and fine PM are able to generate ⋅OH, and induce formation of 8-OHdG. When considered at equal mass, ⋅OH formation shows considerable variability with regard to the fraction of PM, as well as the sampling season. The toxicological implications of this heterogeneity in ⋅OH formation by PM, as can be easily determined by ESR, need further investigation.

Genotoxic and oxidative damage related to PM2.5chemical fraction

“…This finding supports the results obtained in other studies that showed the role of transition metals in reactive oxygen specie production and in oxidative stress induction [11,12]. In different studies the genotoxic and oxidative activity of Cu and Zn are reported [13].…”

Transition Metals in Personal Samples of PM2.5 and Oxidative Stress in Human Volunteers

“…We measured personal exposure to PM 2.5 with portable equipment from BGI (Waltham, MA) as previously described (13). Inductively coupled plasma mass spectrometry was used to determine the concentrations of vanadium, chromium, iron, nickel, copper, and platinum in the aqueous suspensions of PM, as previously described (15,16). The freshly prepared suspensions of PM were filtered through a 0.2 Am Millipore filter (Minisart RC15 syringe filter, Sartorius AG, Gö ttingen, Germany).…”

Inhalation of ultrafine carbon particles triggers biphasic pro-inflammatory response in the mouse lung

“…an electron spin resonance-signal characteristic for organic carbon-centred radicals [30,31]. This feature might be important for hydroxyl generation and downstream effects on cellular oxidative stress [32]. Recently, BECK-SPEIER et al [31] demonstrated the high oxidative potential of UFCP in a cell-free system, as well as the production of the oxidative stress marker 8-isoprostane in exposed alveolar macrophages.…”